Thirteen months on, Liverpool will hope the doubt that lingers and, perhaps, the pressure to make amends can help them pull off what would surely be the club’s most remarkable turnaround since the 2005 final in Istanbul.

“We have no reason to be complacent,” Valverde said. “The result is good, I have no doubt about that, but the tie is still open.”

But Barcelona are stronger too and another collapse, even against a team as dangerous as Liverpool, would be an even greater surprise.

When Roma left the first leg with a three-goal deficit, few could have predicted what would come next. But Barcelona had been stuttering for weeks, flattered by positive results that masked underwhelming performances.